The technology in this application is described in a non-limiting example UMTS Terrestrial Radio Access Network, UTRAN/Wideband Code Division Multiple Access, WCDMA, network that supports High Speed Packet Access, HSPA. A basic example of an UTRAN/HSPA type of system is illustrated in FIG. 1. This example network basically comprises a number of base stations, also called Node Bs 100-1, 100-2; 4, 6, and one or more Radio Network Controllers, RNCs, 200-1, 200-2; 8. A RNC provides control functionality for one or more Node Bs. The RNC 200-1; 8 also communicates with one or more core network nodes in the Core Network, CN, 400, which may be connected to one or more other networks, e.g., the Internet, public and private telephone networks, etc. The RNC and its corresponding Node Bs are often denoted the Radio Network Subsystem, which provides the basic radio access for one or more User Equipments, UEs, 300; 14. There are a number of interfaces in the network. The Uu interface connects the Node B and the UE. The Tub interface connects the RNC and the Node B. The Iur interface connects two RNCs to each other. The IuCS and IuPS interfaces connect the RNC and the CN.
This type of network normally supports a connection state for a UE in which dedicated radio resources are allocated to the UE for communication with the network, and another connection state in which common radio resources such as common Enhanced Dedicated Channel, E-DCH, resources are available to the UE.
The common resources may be released in several ways, for example explicitly by the network or implicitly by the UE. In the latter case, the UE basically maintains the common radio resources until it has emptied its transmit buffer, possibly waiting for an inactivity timer to expire, and then releases the common radio resources. The UE typically releases the resources after scheduling information with a report of empty buffer status has been transmitted to the network, and after the last retransmission process has been acknowledged or the maximum number of retransmissions has been reached. The reception of the scheduling information with the empty buffer status report from the UE will normally be interpreted by the network as an implicit release by the UE, and the network then also releases the resources on the network side.
The inactivity timer, which is also referred to as a timer for implicit release of common resources or simply an implicit release timer, is controlled by the RNC and broadcasted to the relevant UE(s) in the system information. The inactivity timer is normally used because the UE may have new data to transmit just a few ms after the completion of the last transmission. The selected value of the timer is related to the trade-off between releasing the resources as quickly as possible in order to be able to assign the resources to another user and the risk of receiving a request from the same user immediately after releasing the resources.
However, if the inactivity timer in the UE is enabled, it has been noted that there may be situations when the network incorrectly releases the common resources, resulting in radio link failures and data losses.
There is thus a need for a more robust solution for release of common resources in radio communication networks.